"The research group also looked at the impact of probiotics after a course of antibiotics, which wipe out both good and bad bacteria.

Their trial on 46 people, also in the journal Cell, showed it led to delays in the normal healthy bacteria re-establishing themselves.

Dr Elinav added: "Contrary to the current dogma that probiotics are harmless and benefit everyone, these results reveal a new potential adverse side effect of probiotic use with antibiotics that might even bring long-term consequences."